▎ 摘　　要

Transparent and electro conductive materials are of outstanding importance today Their conductivity and transparency are crucial. Since the absorption of one graphene layer is known to be 2.3% it can be used as a reference material. The "conductivity of transparency" is introduced and several literature values based on graphene and carbon nanotubes are compared. (C) 2009 Elsevier Ltd. All rights reserved.